[Hemorheologic and circulatory effects of hemodilution with medium molecular weight hydroxyethyl starch in two concentrations (HAES 200/0.62 10% and 6%)].

: This study was designed to investigate whether the positive effect occurring after infusion of a 10% hydroxyethyl starch solution 200.000/0.62 on cutaneous capillary blood flow could still be increased by using a 6% solution having a lower initial viscosity (HES 6% 200.000/0.62). A single blind study of 10 female volunteers was carried out to study the influence of a hypervolemic hemodilution using 500 ml of a 10% solution hydroxyethyl starch solution at first and that of 6% hydroxyethyl starch solution on macro- and microcirculation, transcutaneous oxygen partial pressure and blood fluidity. After hydroxyethyl starch infusion blood flow in the macro- and microvessels increased significantly. This increase occurred considerably earlier after administration of 6% solution than after infusion of 10% solution. Thus blood flow had already increased after 1 hour and continued to show a tendency of increase over about three hours. 6 hours after end of infusion blood flow had almost dropped to its initial value. The volume effect of the 6% solution immediately after infusion was less pronounced than that after infusion of the 10% solution, but it reached the value of the 10% solution at a later point in time. The course of the haematocrit reflected this process. Average decrease in haematocrit value compared to that following the 10% solution was not as pronounced at hour 3. After 6 hours the decreases were comparable. Similar observations were made of plasma viscosity and platelet aggregation. One hour after infusion plasma viscosity and erythrocyte aggregation had hardly changed but haematocrit had clearly dropped. Thus, blood viscosity at this point in time was essentially lowered.(ABSTRACT TRUNCATED AT 250 WORDS)